Measurement of dislocation core distribution by digital processing of high-resolution transmission electron microscopy micrographs: a new technique for studying defects

A new technique for studying extended defects and dislocation networks is proposed. The approach, based upon the continuum theory of crystal defects. is employed for digital image processing of high-resolution transmission electron micrographs. The procedure starts with the geometric phase method for extracting the lattice distortion field near dislocation cores. Next, the dislocation core distribution (DCD) is recovered from the lattice distortion field. A so-obtained DCD field takes non-zero values only in disordered regions of the lattice. The accuracy of this method is investigated by mathematical integration of the dislocation field over core regions to find the in-plane components of the Burgers vectors. The proposed method is free of topological problems and can be used to study spatial configurations of complex defects in large crystal areas by using a fully automatic computer program. This approach is applied to investigate a network of misfit dislocations in the interfacial region of a GaAs/ZnTe/CdTe heterostructure.